Stabilized nitromannite product and method of making the same



Patented Nov. 4, 1952 UNTED SA ES STABILIZED NITROMANNITE PRODUCT AND METHOD OF MAKING THE SAME corporation of Delaware No Drawing. Application June 15, 1951, Serial No. 231,902

15 Claims. 1

The present invention relates to an improved nitromannite product; and, more particularly, it relates to a pentanitromannite or hexanitromannite product possessing markedly increased thermal stability. The invention also relates to' a method for preparing the novel product as well as to a method for stabilizing pentanitromannite and hexanitromannite.

Hexanitromannite has been used in commercial detonators for many years. While this compound has sufiicient stability for use in certain industrial applications in that under ordinary conditions it may last-for many weeks without decomposing substantially, it rapidly decomposes at elevated temperatures so that there is always the danger that, in the event the explosive becomes subjected to elevated temperatures, the hexanitromannite will decompose to some extent, thus rendering the explosive defective. In situations where elevated temperature conditions may normally be encountered, the instabilityiof the hexanitromannite prevents its use. For} use in detonators for military purposes, moreover, hexanitromannite is of such insufilcient thermal stability as to be of very limited use. The problems of instability with respect to pentanitromannite are similar to those encountered with hexanitromannite.

A principal object of the present invention is to provide a hexanitromannite or pentanitromannite product possessing vastly improved stability at elevated temperatures.

Another object of the present invention is to provide a hexanitromannite product sufiiciently stable thermally to be employed in detonators having wider applicability for both military and industrial purposes.

Still another object of the present invention is to provide a method for stabilizing hexanitromannite and pentanitromannite.

Further objects, including the provision of a method for preparing the novel product, will be apparent from a consideration of the following specification and the claims.

The novel stabilized nitromannite product of the present invention comprises at least one of the nitromannites selected from the group consisting of hexanitromannite and pentanitromannite and a small effective amount of dicyandi amide intimately mixed therewith.

Since, of the nitromannites mentioned, hexanitromannite is the one most commonly employed in the explosive field, its stabilization represents the preferred embodiment Of the present invention, and the invention will be described with particular emphasis thereon. However, it'will be realized that the invention may also be applied to the stabilization oi. pentanitromannite and to mixtures of pentanitromannite and hexanitromannite.

It has been found that the mixing of a minor amount of dicyandiamide with hexanitromannite provides a product which possesses unusually improved thermal stability. This improved thermal stability, moreover, is many times greater than that provided, for example, when other amine compounds are intimately mixed with hexanitromannite.

Hexanitromannite, as is well known, is prepared by nitrating mannitol to provide a nitromannite product consisting substantially entirely of hexanitromannite with small but varying proportions of other nitromannites, particularly pentanitromannite, and of other impurities. The purity of the hexanitromannite product may vary somewhat depending upon the particular procedure and techniques employed in its preparation, and the present invention is applicable to any of the commercial forms of hexanitromannite as well as to relatively pure hexanitromannite. It will be understood, therefore, that herein and in the claims, the term hexanitromannite will refer to somewhat impure commercial hexanitromannite products as well as to relatively pure forms of hexanitromannite.

As stated above, the compound intimately mixed with the nitromannite to impart the improved thermal stability in accordance with the present invention is dicyandiamide. The formula for this compound may be written as follows:

In the preparation of the product of the present invention, it is necessary that the dicyandiamide be intimately mixed with and thoroughly dispersed in the nitromannite. Various methods for accomplishing this will occur to those skilled in the art. A preferred method comprises depositing the dicyandiamide on hexanitromannite particles by wetting the hexanitromannite, which is insoluble in water, with an aqueous solution comprising the dicyandiamide. Upon drying, the dicyandiamide will be deposited on and intimately mixed with the hexanitromannite particles. In this regard, a particularly advantageous method of incorporating the dicyandiamide in hexanitromannite comprises precipitating the hexanitromannite in an aqueous solution comprising the dicyandiamide. For instance, the hexanitromannite maybe dissolved in a suitable solvent therefor, such as acetone, methyl alcohol, ethyl alcohol, methyl formate, methyl acetate, and the like. The concentration of the hexanitromannite may vary between about 20% and about 70%, by weight. The resulting S0111? tion may then be added to an aqueous solution of the dicyandiamide, for example in a ratio of between about and about 35' parts by volume of the hexanitromannite solution per 100 parts, by volume, of the dicyandiamide solution, whereby the hexanitromannite precipitates. The precipitated hexanitromannite may beseparated from the aqueous medium as by filtering, centrifuging, and the like. Upon drying the precipitate, a very intimate mixture of the dicyandiamide with the hexanitromannite is provided.

More than one application of the aqueous solution of dicyandiamide to the hexanitromannite may be resorted to, if necessary or desirable. For

instance, in the. above-described precipitation about 3%, by weight, based on the weight of the nitromannite. Preferably, the dicyandiamide is associated with the nitromannite in an amount between about 1 and about 2%, by weight, based on the weight of the nitromannite.

When the dicyandiamide is associated 'withthe nitromannite by a depositionprocedureas described above, the concentration .ofthe dicyandiamide in the aqueous solution and the amount of solution employed will be such as to provide the. desiredproportion .of dicyandiamide in the final product. Ingeneral, in such a procedure,'it may be said that the proportion of dicyandiamide in the final product will vary directly with the concentration thereof in the solution; and the concentration of dicyandiamide in the solution,

for any particular proportion thereof in the final product, can easily be ascertained.- For example, to provide an amount of dicyandiamide'in the final product of about 1-2%, an aqueous solution containing 3 /2% by weight, of the dicyandiamide i has been found to be suitable (on the basis of 100 cc. of solution per 3 grams of hexanitromannite) The product of the invention and its preparation, and the method of stabilizing hexanitromannite and pentanitromannite in accordance with the present invention, will be more easily understood from a consideration of the following speci fic example which is given for the purpose of illustration and is not intended to limit the scope of the invention in any way:

EXAMPLE Three grams of commercial hexanitromanite are dissolved in cc. of acetone. The resulting solution is added to 100 cc. of a 3 /2 by weight, aqueous solution of dicyandiamide. During the addition, the solution is stirred vigorously, facilitating the formation of a finely-divided precipitate; The final mixture is filtered and the residue is washed with cc. of a 3 /2%, by weight, aqueous solution of dicyandiamide. The product is then dried for several hours at room temperature. The product contains about 1-2%, by weight, of dicyandiamidebased on the weight of the hexanitromannite.

The product prepared in accordance with the above was tested for thermal stability as follows: It was pressed into a detonator cap at a 25 lb. pin pressure. The resulting assembly was then heated to 78 C. and held at this temperature to determine how long it would take for the sample to completely decompose. The sample did not completely decompose until after 273 days had passed, whereas a sample of hexanitromannite without the dicyandiamide, when tested in the same way,

completely decomposed in 1 /2 days.

Mixtures were prepared in the same manner as described above, with, however, 16 amine compounds other than dicyandiamide to compare their stabilizing power toward hexanitromannite with that of dicyandiamide. The various samples were tested in, the same manner' as described above and the results of all the tests are set forth in the following table:

Table I Amine compound employed; pletely-days None 1 /2 Methyl diethanol amine dinitrate 1 Sulfanilic acid .4 A; l-lexamethylene tetramine 2 m-Phenylene diamine 4 Diphenyl p-phenylene diamine 1 p-Hydroxy diphenyl amine 10 a-Naphthyl amine 4 Phenyl fi-naphthyl amine 20 Di-fi-naphthyl p-phenylene diamine 1O Thiourea 15 Isopropoxy'diphenyl amine 2 Nitron J; 1 6 Z-a'min'o 2- methyl 1,3 propanediolgflu l /2' Diphenyl amine-.1; -1 12 f fl-na'phthyl amine 1 /2 Urea 46 Dicyandiamide 273 It will be noted from the above that some of the .amines, such as, for example, methyl diethanol amine dinitrate, sulfanilic acid and diphenyl pphenylene diamine, actually catalyzed the decomposition of the hexanitromannite. Some of the other amines increased the stability of the hexanitromannite by varying degrees, but none of them improved the stability to the extent provided by dicyandiamide. From the foregoing, it will be seen that it is not possible to give anaccurate explanation of the mechanism by which the marked stability of the hexanitromannite is provided by the dicyandiamide.

Considerable modification is possible in the selection of the proportions of dicyandiamide associated with the-nitromannite as well as in the particular method of associating the dicyandiamide with the nitromannite without departing from the scope of theinvention.

I claim:

1. An explosive composition comprising at least one of the nitromannites selected from the group consisting of pentanitromannite and hexanitromannite, and a small amount of dicyandiamide intimately mixed therewith.

2. The product of claiml wherein said nitro' mannite is hexanitromannite.

3. The product of claim 2 wherein said dicyandiamide is present in an amount between about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

4. The product of claim 2 wherein said dicyandiamide is present in an amount between about 1% and about 2%, by weight, based on the weight of said hexanitromannite.

5. The method of stabilizing at least one of the nitromannites selected from the group consisting of pentanitromannite and hexanitromannite which comprises intimately mixing a small effective amount of dicyandiamide'therewith.

6. The method of claim 5 wherein said nitromannite is hexanitromannite.

'7. The method of claim 6 wherein the amount of dicyandiamide intimately mixed with said hexanitromannite is between about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

8. The method of claim 6 wherein the amount of dicyandiamide intimately mixed with said hexanitromannite is between about 1% and about 2%, by weight, based on the weight of said hexanitromannite.

9. The method of stabilizing at least one of the nitromannites selected from the group consisting of pentanitromannite and hexanitromannite which comprises wetting said nitromannite with a solution of dicyandiamide in a solvent in which the hexanitromannite is substantially insoluble, and drying the nitromannite.

10. The method of claim 9 wherein said nitromannite is hexanitromannite and wherein the amount of said solution and the concentration of dicyandiamide therein provides, in the dried product, dicyandiamide in an amount between 6 about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

11. The method of claim 9 wherein said nitromannite is hexanitrcmannite and wherein the amount of said solution and the concentration of dicyandiamide therein provides, in the dried product, dicyandiamide in an amount between about 1% and about 2%, by weight, based on the weight of said hexanitromannite.

12. The method of claim 9 wherein said solvent is water.

13. The method of stabilizing at least one of the nitromannites selectedfrom the group consisting of pentanitromannite and hexanitroman-- nite which comprises precipitating from a solution thereof, said nitromannite in a solution comprising dicyandiamide in a solvent in which the nitromannite is substantially insoluble, and drying the precipitate.

14. The method of claim 13 wherein said nitromannite is hexanitromannite and wherein the amount of said solution of dicyandiamide and the concentration of dicyandiamide provides, in the dried product, dicyandiamide in an amount between about 0.5% and about 3%, by weight, based on the weight of said hexanitromannite.

15. The method of claim 13 wherein said nitromannite is hexanitromannite and wherein the amount of said solution of dicyandiamide and the concentration of dicyandiamide provides, in the dried product, dicyandiamide in an amount between about 1% and about 2%, by weight, based on the weight of said hexanitromannite.

JOSEPH W. LAWRENCE.

No references cited. 

1. AN EXPLOSIVE COMPOSITION COMPRISING AT LEAST ONE OF THE NITROMANNITES SELECTED FROM THE GROUP CONSISTING OF PENTANITROMANNITE AND HEXANITROMANNITE, AND A SMALL AMOUNT OF DICYANDIAMIDE INTIMATELY MIXED THEREWITH. 